Drilling muds



Patented h'layd W45 i 4 v hearse stares earner entree arrears panama Mans Robert E. Booth, Sprlngdale, Eonn... acsignor to American Cyanarnid Company, New llorlz, N. 22, a corporation oi Maine No Drawing. Application December 19, 1941,

Serial No. $23,603

a 14 Claims. (cl. 252-8.5)

This invention relates to a method of control- -such asbarytes, iron oxide, magnetite or other ling the viscosity characteristics of aqueous mud magnetic materials in finely divided form, and or clay dispersions of the type used in drilling the like. Frequently preliminary conditioning oil, gas or other deep wells. Although some of or viscosity reducing agents are also added to the the treating agents used in practicing the inven- 5 mud such as the Water-soluble salts of polyphostion are of considerable value as preliminary phoric acids and particularly the alkali metal viscosity reducing reagents the invention in its salts such as sodium tetraphosphate and tetrabroader aspects is directed particularly to the sodium pyrophosphate and the water-solublesalts problem of preventing the phenomena of thickof metaphosphoric acid such as sodium metaening and rethickening in such muds, which w phosphate, sodium hexametaphophate and the phenomena occur as a result of conditions enlike. Sodium silicate, tannic acid, waste sulfite countered during the drilling process. liquor, quebracho-soda, humic acid, lignic acid In the drilling of oil wells and other deep and pyrogallic acid, usually also in conjunction wells by rotary drilling processes it is now thewith free alkalies are also frequently used as prepractice to recirculate a fluid called drilling s liminary conditioning agents and all or most of mud downwardly through the hollow drill pipe, these materials have also been added to the mud across the face of the drill bit, and upwardly ng its subsequent use in drillin in order to through the drill hole and well casing. The drillmaintain 9a reduced V S W- ing mud serves to cool and lubricate the drill bit, A satisfactory ri lin mud mus p sses c to raise the drilling cuttings to the surface of the 20 t m definite characteristics. It must have sufground and to seal the sides of the well to preflcient fluidity to permit pu ping at the p p r vent loss of water and drilling fluids into the te tho excessive er q ents a d formation through which the drill hole is being must e B l i tly thixotropic in character to bored. After each passage through the well the prevent the settling of sand and cuttings in the mud is usually passed through a settling tank or 25 well when the circulation is stopp p rarily trough, wherein the sand and drill cuttings are e in t fishing fo too s 01 for 0thseparated with or without screening; after which er purposes. The two most important properties the mud fluid is again pumpedinto the drill pipe of rotary drilling muds are the property of denby amud pump. sity and the property of'viscosity and shearing Drilling muds consist of aqueous clay disper- 3 strength, which last property is controlled by sions, with or without added materials of the the colloidal dispersion of the mud and its gradtypes hereinafter described. The clays used in nation of particle 'siz'e. Viscosityand dispermaking up the aqueous dispersions are obtained S on are usually c ns d simultaneously W from the most varied sources; in oil 'welldrilling density, the problem being to obtain adequate they are sometimes found in the well itself, at 35 density, low viscosity anda permanent suspenother times they are dug from deposits of clays sion of clay solids capable of supporting sand particularly suited for the purpose, while in many and cuttings within the well but which will recases they may be compounded from mixtures of lease the sand and cuttings outside the well; natural clays with added gel -forming materials The viscosity in thixotropio mud may be meassuch as bentonite and added weighting materials 40 ured by the Marsh funnel 'viscdsimeter and the resultsareexpressedasthe number of seconds "fora given volume to fiow through anlorificeiiu -wo predeterminedsiza :Inmuds cfthis chars I Y I acter tlie measured:viscosity dep nds to a consid i a i erable extent an movement: or i on the; elapsed; i i time sincezmiovement has ceased, 1 as one of the I chief a antrim tmg factors roams: viscosity: is the a tendency of? themud toirorm a gel upon stand i I ing. Tl'iisproperty of thixotropyor geiationupon i g i standing; has been described as resulting from i j i the preserme or a shell; of surfacehydrationsurrounding each may particle and separating it i i j from other clay particles similarly hydrated. The j normal: forces ofattraction betweentheparti cle's areopposedby forces-ofrepulsion existin 4 "byivirtueof thesevshelis ofsurface'hydration.

v i theiresult thatg' relative; movement between the clay particles is hindered and {themud has a i I increased concentrations of treating or viscosityreducing agents which contain metallic elements, such as the alkali metal polyphosphates and silicates referred to above, or of their decomposi tion products, and is also frequently encountered when quebracho is used.

I have discovered that the phenomenon of thickening and rethickcning in aqueous thixotropic clay dispersions of the type used in drilling muds can be delayed and in many cases com pletely avoided by the incorporation therein of suitable amounts ofwater-soluble organic com pounds of a certain well-defined class. The compounds which I have found to possess this 'importa'nt property are all water-soluble non-ionic nitrogen-containing organic compounds which have in the same molecule at least one acidic group and at'least one NR1R2 group, wherein R1 and'Rz are non-ionic organic substituents which do not impair the water-solubility of the compound as a whole; In the most important mud treating agents of my invention the roups R: and R2 are either hydrogen or lower alkyl radicals, although non-ionic organic radicals of higher molecular weight may be present if the compound as a whole is water-soluble; It should be noted that the term "acidic group in the above definition means an acidic group which forms a part of the molecule of the organic compound and is not dissociated therefrom when the compound is dissolved in water,'as is the case with amine salts. .The most important organic compounds falling within the scope of the above definition are the water-soluble monoand diamides of organic acids, the water-soluble amino It: is i a; principal object or the: pre ent inrerrticnto provides; class of mud conditioning mIa-i teifials which have the property of delaying or a 1 inhibiting the thickening or rethickcening of drill v muds; ThB phenomenon of thickening 0 I i curs: as a chara'ct'eristic rise: in viscosity accome 1 panied by consi era e fle cu a in io se li f i f the dis er ed clay particies'in the mud, and may i :resuiteither :rrcm iheati'ng' of "the mud 2 by i i-he, j heat normally encountered in :deep wens; andby 1 1 I v f friction pumping and recirculating; o irmm n the action of salt or lime or other; inorganic-ions 1 encountered; from subterranean mines or from 1 i I 1 f Y cement used in sealing the well, Kori both; 7 i I g I i thickening of the mud is substantially the same j I phenomenon t ckenin but is esign e as:

- i rethickening when it occurs after the mud has 7 I j ori na ly b'eenthinned by theiaddition or wateri E Esolublei poly hosphates or other; conventional vis-K i ccsity reducing agent; Rethicltening I or reflccculatio'n of drilling muds occurs as a result of 1 amido derivatives of other compounds contain 5: the like. Manyzof' these may bezused in the form v a v v ipropyl 2 acetamida diacetamide; iaEnd the like 94a,; which; has new 7 matur d into:

2;3l8 ,2 84, rgrantedlvay:4,:1953,

@ i I i Another: important class mo ume tain 7 i i (0 ing organic'compounds are theamides and imides 1 of aliphatic and cycloaliphatic carboirylic acids which are solubilized by sulionation and used in the form of their alkali metal sulfates or sulfonates. Thus, for example, the amides and imides of maleic, f'umaric, itaconic, citraconic, glutaconic, aconitic and other aliphatic diand polycarboxylicacids can be sultonated by heating with an aqueous solution oi. sodium sulflte or I bisulflte and thus transformed into amides and imides of sulfosuccinic, sulfoglutaric and who.-

tricarballylic acids respectively.- Suliosuberic, sulfopyrotartaric and sulfoadipic acid amides and imides can be prepared by similar methods and" used for controlling the viscosity of aqueous drilling muds. Similar reactions with hydroxy aliphatic polycarboxylic acid amides and imldes such as malic, citric, tartaric and-the like will produce the corresponding sulfates which are suitable for use, although less stable against decomposition by heat. Y

The water-soluble amino-acids form another important class of viscosity-controlling reagents for use in drilling muds and other aqueous thixotropic claydispersions. Simple amino-monocar- 6 5 boxylic acids such as glycine, glycocoll, the alanines the leucines, valine aminobutyric acids such as'the alpha-amino compound and the like ar important agents for the prevention of rethickening both when used alone and in con- 7 junction with water-soluble poLvphosphates, such as sodium tetraphosphates, tetrasodium pyrophosphate and the like-as well as sodium silicate and other similar chemicals which tend to rethicken the mud upon continued addition. The corresponding alkyl and acyl substituted amino carboxylic acids and 7 the water-soluble amino cr' ing acidic groups such as phenols I aromatic n troso compounds, sulifonated aromatic amide'sa'nd er amine salts if gdesirei; an: t anion? oi the i amine salt does not iunction as a partof the: i compound as, it is dissociated, uponsolution in a.

n t :The water soiuhle aliphatic acid amides which f i mayheused to prevent thickening andrethicken-H am imm mu s? a e those t w I 'phatic :monoand i polycarbo'xylic acids such as 1 i formic, acetic, propionic, etc. up to and including ini-caproic acid, the amide of; which is moderately v f I water-soluble, corresponding monoand I I i w ami e e v l nt mole ar w ht! I a i m y el e he 1 5 s su h 5 eeew ami r I z i acetodimethyiamidep :a t e hr m fi r s tefii-h eithylamide, mixed dialkyiainid'es such as methyl water-solub e amides of aliphatic i i-i and poly 1 i thiourea; al wl er arylg s bstit i di'ureas such as 7 yl e h lear nd r m ur an i 2 3 urea; phenyl urea and thiourea, succinamic; and a 1 a meth smam c ac d a d the r a ka imeta z I a and ammonium salts and thecorresponding inonoi amides of; glutaric and lower: alkyl ,glutaric acids; i E and their; Water-Soluble salts iRepresentathre Z water-soluble aromaticamidies that may be eme a :pioyed are anthraniiic. acid, and itswatet-soiuble l I salts; o-amidophenql, f and the; like. Another int,- portant' member; of this class is solubfli z 5 1 ;;application Serial INo. 385,470, filed Mar n 27,; Patent ;No.: I l

" drilling muds.

tuted thioureas including methyl, ethyl, propyl,-

butyl and higher monoand diallryl ureas and thioureas as viscosity controlling reagents for aqueous clay dispersions, and particularly for These applications have now matured into Patents No. 2,280,995 and 2,280,994, respectively, both dated April 28, 1942. l"he present application is a continuation-impart of these two earlier-filed applications, by reason of the fact that the compounds described empirically as reagents for preventing rethicltening in clay dispersions are members of the broad class defined above. Further investigation with other representative members of this broad class led me to a recognition of the fact that the entire class of water-soluble organic nitrogen compounds containing acidic groups is available as protective agents for preventing the thickening or rethickening of mud dispersions, and this constitutes the basis of my present application.

Although my present invention is not to be limited by any theory of action of the compounds involved, I believe that the important properties of the class in question are due at least in part to their buffering-action on the clay colloids; which buffering action results from the presence of both acidic and amino or amido groups in the same organic compound. .Clays forming thixotropic mud dispersions are zeolitic in character; that is' to say, they. contain a nucleus composed ofaqlumina and silica and a more strongly basic portion which is usually subject to ion exchange. I believe that the adsorption of excessive amounts of strongly basic ions, such as sodium or calcium soluble salts have shown that these compounds are effective to delay or inhibit an excessive rise in the viscosity of the mud, and I believe that this result is due to a bufiering or protective action which prevents ready accretion of excessive positive ions by the clay particles.

From the foregoing it will be seen that my present invention is directed primarily to the provision of a class of compounds that are designed to supplement the mud treating chemicals now in use, rather than to replace them. As has been noted above, a large number of water-soluble mud treating chemicals containingpositive ions are now in use for this purpose, the-most important.

being the water-soluble salts of polyphosphoric acids such as sodium tetraphcte, tetrascdium pyrophosphate. sodium metaphosphate, sodium hexametaphosphate, sodium acid pyrophosphatc, sodium silicate, quebracho, quebracho-soda, and th corresponding potassium salts. One or the most important advantages of my invention resides in the fact that the water-soluble non-ionic organic compounds containing both acidic groups and amido or amino groom may be used with success to oflset the rethickening that occurs when excessive quantities of these phosphates and similar compounds are added to drilling muds.

The invention in its broader aspects is not limited by the method used in incorporating the organic nitrogen-containing compounds of the present-invention with the mud or clay dispersion and any suitable method of incorporation may be used. In well drilling one method that has been employed with success is to mix a solution of the compounds, which solution may or may not contain other viscosity reducing agents as noted above, with the mud as it comes out or the well to facilitate the screening or settling out of sands and cuttings. In other cases themud treating composition may be added just ahead of the mud pump so that the pumping operation may assure a thorough mixing. Still another method is to introduce a solution of-the treating composition 7 into mechanical de-gelling mechanisms, and other methods may be resorted to if desired.

-.However, it should be noted that the remarkable property of the organic compounds containing,

both acidic and amino or amido groups in' deflocculating a mud fluid that has already been thickened by heat or by inorganic salts, or that has been re-thickened by the addition of excessive amounts of other viscosity reducing agents renders this material of especial value as an addition agent to mud fluids that have already been used for some time,- and in many cases the treating agents of the present invention may not be added to the mud until after the first few days of a drilling operation employing fresh drilling mud and other deflocculating agents.

The nitrogen-containing organic compounds with polyphosphoric acids such as tetrapho sn phoric acid, metaphosphoric acid and polypyrophosphoric acids and the incorporation of such amine salts of polyphosphoric acids, which are themselves defiocculating agents for drillin muds, constitutes another important feature of the invention. In addition to amines, other organic nitrogen compounds such as dicyandiamide will also'formsalts with polyphosphoric acids and may be employed in the same manner.

In ordinary drilling practice the mud conditioning agents are added in amounts less than 0.4 pound per 42 gallon barrel of mud, and

quantities of 1 pound per barrel are seldom exceeded in any single treatment. However, as continuous or intermittent additions may take place over considerable periods of time it is impossible to define the proper concentration in terms at the quantities added and this must be determined in the field. It should be understood, therefore, that the present invention includes the addition to mud or clay dispersions ofdicyandiamide or composition containin this material in any amounts which, in the 7 Exam: judgment or the operator, will give the proper viscosity that may be desired for the purpose In order to demonstrate the value of dicyin mind."

andiamide and urea for thinning or deflocculating rethickened drilling muds, samples of the mud described in Example 1 were first treated with tetrasodium pyrophosphate until the visgreater than tbe'initial value. Successive additions of dicyandiamide and of urea, tively, were then made to these samples resulting visoosities determined. The procedure followed was the some as that described in Example '1. 4 4 follows A drilling mud dispersion having a. specific 15 The invention will be illustrated in greater 5 detail by the following specific examples. It should be understood, however, that although these examples may describe in detail some of coslty w .the more specific aspects of the invention they are given primarily for purposes of illustration pe and the invention in its broadest aspects is not nd t e limited thereto.

The'results were as Ekmu3 EXAMPLE 1 gravity OfO 1.32 was made from McKittrick clay,

Ms M??? .1% 00578857 um mm censuses m V( .W;

m Wm 5050505. m m direzss m s w m p mmm mm mem m wm e m m mm m dmma mm d e7 me m .m w e n s rm a me O d e m rm W t r C .r 4 o mtmmm mfimmm m m mmd m n md n m fim mwvfiws s m mswmm m e fl m d h m d m nmmm m amas meeas womrw oammmw the iimnel to number of seconds required for discharge.

.I m e. emwlnv. msmm re mm m u w um nw mews s s smm w mmm ms wmdmmmm Mmm m Hm flfiw u w m.me m em m MHHWM m dumb l m @m m m m t wam m mm Mme 3 en t. m s 3 31.1, w m m s mmmwmmm mnmd m mm dwm n mm mwt m xmmoomm o a umm mu fi sm mm mmfimmm mmm mmw V t d t m mmwmmmmm msmmmmwm 0 .d 0 .0 e1F r d m.-fge% mm smmmmem t mu m 3m m mmmm m m w w m m s m i ms m mv. wm mm 0 m .m m .H bd m mmma 5 m.m m m m mm mmm mm s mm mm H b w 4 u mm sm mm mwn fiwm m 2 3m we tkm fim sw m mm m .nfldm dmmmmmwmmu m m mm h m nm fiwmm emmm mm msm m m mm mm m m md w m m .masoeemm smm ma s mm mm imwc DH w e PM TSP? mnumannnnnnnn thi-ougha. screen into a, Marsh funnel viscoslmnmnwuannnmaunaunnann ggg Ureo Thioureo s-rr mmnunnnnmmaumunumnnnnnnmmu TSPP munmnnnnnnmnnnndnmn may 1,32,?

mnwmummmmmmammmm Control testno reagent LbsJbbl. cumuhtive 5 in shaleiermations that give viscosity troubles in drilling operations. This mixture approached very ciessig a type of drilling fluid actually employedjln'drilling. To various samples oi the dri ling mud was added varying amounts of 'nigrosine, tetrasodium pyrophosphate (TSPP), sodium acid pyrophosphate (,SAPP), and 50% mixtures of nigrosine with sodium acid pyro= N igrosine L ed-005388002050 anaanaaaasnua SAPP +02 m50430s-500 can mnaawnaanw.

Marsh funnel viscosity, seconds 1507 Tar"? mwwmmmmmmmm TSPP mmmwmmm phosphate and tetrasodium pyrophosphate. The Marsh funnel viscosity of the various mixtures was then determined with the following results:

Lbs-[b131- renumber firs m m at m m n mm mana e mm mesa we mm m en agements n aaann aaanamnaw l att sts m 1. nannaaaa m 40 o STP STP STP nnnaaamaaaaaannnmannn 2 0 err munmnnnnnnumnmmmmmmm er cent urea No control tests are shown in which phosphate is added to mud fluids containing 2% and 3% of test with'lgs/bbl.

eter. The viscosity is expressed as the of seconds required for the funnel to discharge.

NaCl but no organic nitrogen compound because 5 the viscosity remained too high to measure, even after substantial amounts of phosphate were added.

Itercent NaCl n am nnmaae ExAmrLn s =Z11Z9 thiourea instead of urea. o a dicyendiamide instead of urea.

Viscosity tests were made on. .700 cc. samples of the mud of Example 3 to which 0.5 gram of Ca(OH) 2, equivalent to 500 parts per million of Ca++ ions, had been added. The procedure was as described in the preceding example. The results are shown in the following table:

0 0726864214 6 mn anwannnaan a dS w 4382294354 "0 new enaannnnnn 70MB 0 1 as attsta e mw nnnamannn n ttb t W w nmnunnnw m m m u n M9321 r n 5 7 32 U u 0 case n P m T S h h m n t m h s mm C S It is noted that the addition of small amounts 60 of nigorsine reduces considerably the viscosity addition of sodium acid pyrophosphate decreases the mud viscosity almost as well as nisrosine but excessive amounts tend to rethicken the mud. A -50 mixture of nigrosine and sodium acid pyrophosphate is seen to be more efiective as a viscosity controlling agent than either 0 nigrosine or sodium acid pyrophosphate. Tetray critical and theaddition of slightly excessive amounts raised the viscosityof this mud to a very high figure. When added to the mud with of the hydrated mud mixture and the addition may be continued over a wide range without increasing unduly the viscosity of the mud. The

sodium pyrophosphate appears to be ver in its effect Exsmm 5 v A drilling mud of a specific gravity of 1.31 was prepared by mixing 4 parts by weight of Ville y standing. The Ville Platte clay was a Platte clay and 1 part by weight of a bentonitic clay and water and allowing the mixture to hyllzcuis ena clay relatively low in colloidal matter whereas the bentoniticclay used was a highly V V colloidal clay representative of the land found w an equal proportion of nigrosine it is observed,

drate b and aminoaikyl radicals, X being an r aa'rasis aqueous drilling muris which comprises incor-.

poratmg glycine therein.

9. A s w fluid 60111131151518" a thixotropic aqueous clay. dispersion and a water-soluble organic compound corresponding to the formI ila RCOX in which X is a member of the group consisting of hydrozwl and amido radicals and R is a men,

her or; the group consisting of hydrogen, aliwi amide group whenRishydrogen oralkyi. i

0, A driilingfiuid comprising a thixoiropic aqueous clay dispersion and a water-soluble moniomc organic compound containing a carbamyi group.

'11. A fluid. comprising a thixotropic aqueous clay dispersion song a viscosieyreciucing agenr capable of rethickening the fluid on; also containing a water-=so1uble non-dome organic comgummi having combined therein a carbamyi group.

12. A g fluid comprising a otropic aqueous ciao dispersion and; a water-soluble lower aliphatic carbomlic acia amide. H

13. A drilling fluid comprising a .thixom'opic aqueousciay riispersionand a water-soluble am!- no carboxylic acicl.

- 1 .4. A who fluid comprising a tmxotropi aqueous clay dispersion and a water=soiubie lower aliphatic amino carboxyiic acifil.

" T B. 00m. 

